Formation of Micro‐Patterned Ga₂O₃/Se Heterojunction and its Application to Highly Sensitive Avalanche Photodiode

Abstract

Herein, the formation of square‐shaped micropatterns of a Ga2O3/Se heterojunction avalanche photodiode (APD) at an active area of 10 μm × 10 μm and its application to a visible light sensor with high sensitivity by amplification of photocurrent density for the first time are reported. The miniaturization of the Ga2O3/Se APD improves its signal‐to‐noise ratio (SNR) by 10 dB as compared to the expected SNR. This is possible because of the improvement in thermal radiation and reduction in resistance loss. The effects of scaling on the photovoltaic conversion characteristics of Ga2O3/Se and TiO2/Se are investigated by varying the active area from 100 μm × 100 μm to 10 μm × 10 μm using photolithography and etching. A remarkable increase in the external quantum efficiency is observed for miniaturized Ga2O3/Se heterojunction APD at widths smaller than 50 μm × 50 μm by a combination of avalanche amplification and the micro‐scaling effect at a bias voltage of 15 V.